Lump on the bottom of my back?

I went to the doctors around 5 months ago with a small lump on the bottom left hand side of my back. My doctor said it was possibly a small lipoma and ordered an ultrasound and a possible fine needle biopsy if the radiologist doing the ultrasound thought it was necessary. The radiologist said he couldn't find anything on the ultrasound, and this, combined with it being so small said it was almost certainly nothing and opted to not bother doing the fine needle aspiration. The way I understood it, due to the lump being small the results would be inconclusive and they wouldn't get enough cells from the biopsy to make a diagnosis. The radiologist suggested I go back if it started to clinically grow, he wrote up his notes and passed them on to my doctor. My original doctor who referred me for the ultrasound read the notes and got back to me a week later. He said he agreed with the radiologist's diagnosis and if it clinically grew to go back and they would do an mri. Now 5 months later I feel like the lump has grow, not majorly so but enough to make me a little anxious about it. Is going back warranted? What does clinically grow mean? I don't want the doctor to think im a hypochondriac but im a little concerned. Im going back tomorrow, what are the main questions to ask because I would like to get to know what it is. Thanks